With the spread of the omicron variant and COVID-19 boosters open to those in the U.S. ages 16 and up, some are wondering what the future holds for boosters. Will we also need a fourth dose, as Pfizer CEO Albert Bourla suggested recently? Should we be prepared to get boosters for the next few years until COVID-19 is fully under control? Or will we need an annual shot, like the flu vaccine, for the rest of our lives?
Right now, experts don't know how many COVID-19 boosters we'll eventually need or how frequently we'll need to get them. But there are some key factors that they're paying attention to in order to figure that out.
Boosters may provide longer-lasting protection
Boosters are designed to do exactly that — to boost your body’s initial response to a vaccine and provide more protection against a particular pathogen. And it’s not that unusual for a vaccine aimed at preventing a viral illness to require boosters, Dr. Bernard Camins, medical director for infection prevention at the Mount Sinai Health System, told TODAY, pointing to the two-dose childhood measles, mumps and rubella vaccine. “In this situation, we’re finding out that even with the COVID-19 vaccines, you do need boosters,” he said.”
Researchers are looking at two major factors that will determine whether or not we'll eventually need more boosters. First, does the protection provided by the vaccines wane over time? And second, are the current COVID-19 vaccines still relatively well matched to the version of the virus that’s circulating right now?
If the protection dissipates over time, as appeared to be the case with the initial two-shot doses, then we might eventually need another round of boosters to amp up our immune responses.
"After six months, Moderna and Pfizer immunity wanes. And the idea behind boosters is exactly that word: Let's give your immunity a lift and get these antibody and other responses back up to a level that is more protective," Dr. Gabor Kelen, professor and chair of the department of emergency medicine at Johns Hopkins University, told TODAY.
As that immunity waned and the delta variant took over, we saw more breakthrough infections among vaccinated people. (Although the rates of hospitalization and death due to COVID-19 remained very low among vaccinated people.)
"The big question now with the Moderna and Pfizer vaccines is whether this third dose is going to provide longer-lasting immunity or if this is something where we'll need booster shots periodically," Dr. Thaddeus Stappenbeck, chair of the department of inflammation and immunity at the Cleveland Clinic Lerner Research Institute, told TODAY. "That I don't think we have the answer to yet."
Future booster shots may be targeted to specific variants
If a coronavirus variant emerges that appears to significantly evade the protection we have from current vaccines, a new booster might be required to account for that. And future COVID-19 boosters may target specific coronavirus variants.
"There was some mismatch between the vaccine and the delta variant, but it wasn't dramatic enough to make the vaccine ineffective," Camins explained. "With omicron, there's actually more mismatch."
Preliminary data released last week suggests that three doses of the Pfizer-BioNTech COVID-19 vaccine produce a protective immune response against the omicron variant that’s comparable to two doses of the Pfizer vaccine against previous variants. But the results from a lab study (shared in a press release) also show that those who received only the primary two-dose series have a significant reduction in protective antibodies compared to those who also received a booster dose.
Those findings will need to be replicated with real-world data before experts can make any conclusions about the effectiveness of Pfizer's vaccine against omicron — or whether or not an entirely new COVID-19 vaccine is necessary.
Both Pfizer and Moderna already announced they’re working on omicron-specific versions of their vaccines and expect them to be ready in March 2022, should they be needed. “If it’s more targeted, you’re probably going to see fewer breakthrough infections with that booster,” Camins said.
For now, "all of the vaccines are the original variety," Kelen said. If omicron doesn't end up being any more dangerous or lethal than previous variants, we may not necessarily need a new vaccine.
"If you put all your eggs in omicron, by the time you get that (vaccine) out six months later we'll have (another variant)," Kelen said. "So as long as the vaccines work reasonably well for any variant that comes along, you wouldn't necessarily need a newly produced, very directed vaccine."
But there may come a time when a new variant "really does avoid or escape" the immune protection provided by the vaccines, Kelen said. And at that point, a new version of the vaccines will be necessary.
Will we need a COVID-19 vaccine every year?
For now, experts say it's too early to tell whether or not we'll need more boosters or for how long we should expect to receive them.
Many experts anticipate that COVID-19 boosters will end up being like your yearly flu vaccine, Kelen said, adding that we may one day have an annual combined flu and COVID-19 vaccine. (In fact, Moderna is already working on it, Reuters reported.)
"The population in the U.S. and many countries is just not willing to get to the level of herd immunity," he explained. So we'll likely be dealing with the coronavirus in some form or another for the rest of our lives with different variants "swirling around." But whether or not that means we'll also need to get boosters every year for the rest of our lives isn't known yet.
To determine whether or not another dose is needed for omicron, "what we're going to have to do is just monitor breakthrough infections," Stappenbeck said. If we start to see more and more of those beyond what researchers would expect, "the decision will be made to consider a fourth dose. And I think that would be perfectly reasonable," he said.
"I think it may be somewhere in between," Camins said. "Six months from now, it may be that we'll need it again. But I don't know if it's going to be lifelong like the flu vaccine." Ultimately, the more people who remain unvaccinated the more likely it is that more cases and, potentially, more variants will emerge that necessitate added boosters, he explained.
And if you haven't gotten your initial series or third dose yet, experts say you shouldn't let the possibility of more boosters dissuade you from getting this one now. Not only does the booster significantly increase your protection from COVID-19 infection, but it also makes you less likely to transmit the virus to others, Kelen said. "So it's both for your own protection and for you to protect other people as well."